1. Field of the Invention
This invention relates to powershift transmissions, or transmission sections, utilizing multiple identical, or substantially identical, countershaft assemblies.
2. Description of the Prior Art
Change gear transmissions, or transmission sections, utilizing multiple substantially identical countershaft assemblies normally driven by an input shaft or input gear and driving an output shaft are well known and widely used, especially for heavy duty vehicles such as trucks and the like. Such transmissions, especially when provided with floating output shafts or mainshafts and/or floating output or mainshaft gears, are highly advantageous as each countershaft is required to carry only an equal portion of the torque load. Examples of such transmissions and a more detailed discusison of the structure and advantages thereof may be seen by reference to U.S. Pat. Nos. 3,105,395 and 3,500,695, both hereby incorporated by reference.
Powershift change gear transmissions are known in the prior art as may be seen by reference to U.S. Pat. Nos. 3,802,293; 3,362,245 and 3,675,508, all hereby incorporated by reference. The advantages of powershifting transmissions, i.e. transmissions providing continuous power from the input to the output thereof during a ratio shifting operation, for certain situations is well known in the art.
Overlapping clutch engagement, as is often a feature of powershifting transmissions, is also well known in the art as may be seen by reference to U.S. Pat. Nos. 3,762,518 and 3,783,985, both hereby incorporated by reference.
While the powershifting transmissions of the prior art have been generally satisfactory, the designs thereof are subject to improvement as structure providing the use of torque sharing substantially identical multiple countershafts in known powershift transmission designs is not seen.